Heretofore, pneumatically operated machines have been available for injecting paint and the like into precharged aerosol cans. As illustrated in U.S. Pat. No. 3,797,534, such devices commonly included a manual lever for lifting an aerosol can to be charged into contact with a relatively small reservoir, e.g. one quart. A pneumatically operated piston drove the paint from a cylinder at the bottom of the reservoir through the aerosol valve into the can.
Further developments involve automation of such equipment. Typical of the direction the art has taken is shown in U.S. Pat. No. 4,938,260. Such devices merely attempted to add mechanical elements and sensors to replace the manual input of the operator. For example, sensors detect the location of the can and allow a pneumatically adjustable platform to position the can to be filled, and a metering pump is monitored and controlled in order to measure the filled charge within each can.
However, although these and other improvements have been directed toward a more automated filling device, other problems within the art remain unaddressed. For example, the emission of volatile organic compounds, or VOC's, has been a source of government regulation, and continues to be a problem for such devices. Further, the reason why a single unit aerosol filling machine continues to be developed is because of a market driven need toward custom coloring and filling of paint into aerosol cans. To meet such a need, the older manual devices perform superior to a pneumatically controlled device in terms of cost, availability, reliability, maintenance, and other real-world factors that arise when a point of purchase retailer is asked to operate and maintain an automated filling device better suited toward high volume, industrial applications.
Finally, another disadvantage of the prior art resided in that open topped reservoirs tended to lose solvent by evaporation and skin over, as well as both solvent and propellant due to over-pressure blow-by. And, a mechanical aerosol can lifting mechanism adds an element of potential operator error. If the lever were misadjusted such that the operator could urge the aerosol can against the reservoir too firmly, the aerosol can could be bent or damaged. Such over pressure or analogous underpressure between the can and the reservoir could cause leakage of the paint. During an attempted filling, the paint could spray under pressure over the base and other portions of the filling apparatus. The spilled paint could readily interact with the lever and lift mechanism causing binding and sticking.
A search of the prior art did not disclose any patents that read directly on the claims of the instant invention; however, the following other references were considered related:
______________________________________ U.S. Pat. No. Inventor Issue Date ______________________________________ 5,832,965 Fasse et al. 11/10/98 5,535,790 Hirz 07/16/96 4,938,260 Hirz 07/03/90 3,244,494 Apple et al. 04/05/66 4,727,914 Anderson, III et al. 03/01/88 5,263,519 Reyner 11/23/93 ______________________________________
The present invention provides a new and improved aerosol can filling apparatus which overcomes the above referenced operator safety and other drawbacks of the prior art.